ICD-10 Code E05.3 – Thyrotoxicosis from ectopic thyroid tissue (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E05.3 – Thyrotoxicosis from ectopic thyroid tissue
What it is
This code identifies thyrotoxicosis caused by functioning thyroid tissue located outside the normal thyroid gland. Use it when excess thyroid hormone comes from ectopic thyroid tissue, not from the usual gland.
Clinical signs
Clinical features vary; refer to documentation. Typical thyrotoxicosis findings may include weight loss, heat intolerance, palpitations, tremor, anxiety, or other hyperthyroid symptoms, with the source documented as ectopic thyroid tissue.
When to use this code
Use E05.3 when the provider documents thyrotoxicosis due to ectopic thyroid tissue, such as thyroid tissue outside the neck producing excess hormone. This code supports cases where the abnormal tissue source is clearly identified. If the record only says hyperthyroidism without the ectopic source, check documentation.
Do not use for
Do not use this code for thyrotoxicosis from the normal thyroid gland, Graves disease, or thyroiditis. Do not assign it when ectopic thyroid tissue is present but not documented as the cause of thyrotoxicosis.
Coding tip
Code E05.3 only when the record links thyrotoxicosis to ectopic thyroid tissue; otherwise, query for the specific cause.